Zoom lens

ABSTRACT

A zoom lens includes sequentially from an object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, a fifth lens group having a positive refractive power, and a sixth lens group having a negative refractive power. The zoom lens varies the interval between the lens groups to perform zooming; shifts the second lens group in a direction substantially orthogonal to the optical axis to correct image blur occurring with optical system vibrations; and satisfies given conditions, enabling a compact size and a high zoom ratio to be achieved while improving imaging performance.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to a compact zoom lens that achieves wide angles, has a high zoom ratio, and is suitable for digital imaging apparatuses such as digital still cameras and digital video cameras.

2. Description of the Related Art

Reductions in the size of digital imaging apparatuses such as digital still cameras, broadcast cameras, and surveillance cameras have advanced. Accordingly, zoom lenses that are compact and, have a high zoom ratio and high imaging performance are demanded as imaging optical systems for use on such digital imaging apparatuses.

To address such demands, several zoom lenses are known that sequentially include from an object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power that is followed by 1 or more lens groups (see, for example, Japanese Patent Application Laid-Open Publication Nos. 2011-33868, 2012-98699, and 2009-282398).

The zoom lens recited in Japanese Patent Application Laid-Open Publication No. 2011-33868 has a zoom ratio on the order of 9 to 41.2, and an angle of view at the wide angle edge on the order of 68.4 to 79.6 degrees. The zoom lens recited in Japanese Patent Application Laid-Open Publication No. 2012-98699 has a zoom ratio on the order of 33.5 to 44.25, and an angle of view at the wide angle edge on the order of 74 to 84 degrees. The zoom lens recited in Japanese Patent Application Laid-Open Publication No. 2009-282398 has a zoom ratio on the order of 9.7 to 19.4, and an angle of view at the wide angle edge on the order of 74 to 84 degrees.

Although the zoom lenses disclosed in Japanese Patent Application Laid-Open Publication Nos. 2011-33868 and 2012-98699 have a sufficiently large angle of view at the wide angle edge and a sufficiently large zoom ratio, the maximum image height at the wide angle edge cannot be said to be sufficiently large and high imaging performance cannot be achieved. If the image height at the wide angle edge is increased, the diameter of the optical system has to be increased. However, if the diameter of the optical system is increased, the overall length of the optical system accordingly increases. In either case, a compact size for the optical system cannot be maintained, making use on a compact imaging apparatus difficult.

Further, the zoom lens disclosed in Japanese Patent Application Laid-Open Publication No. 2009-282398 corrects image blur by moving the third lens group in a direction orthogonal to the optical axis. Nonetheless, in the zoom lens, the anti-shake coefficient (amount that image shifts/amount that anti-shake group is shifted) of the third lens group at the telephoto edge decreases and therefore, the distance that the third lens group is moved to prevent blurring at the telephoto edge increases. As a result, the imaging performance when blur is corrected deteriorates. Further, a large area for the third lens group to move has to be established, inviting increases in the size of the optical system. In addition, the mechanism for driving the third lens group also has to be of a larger size.

Since the zoom ratio of the zoom lens disclosed in Japanese Patent Application Laid-Open Publication No. 2009-282398 is on the order of 9.7 to 19.4, compared to that of the zoom lenses disclosed in Japanese Patent Application Laid-Open Publication Nos. 2011-33868 and 2012-98699, the zoom ratio is insufficient. However, if the zoom ratio is increased, the distance that the lens group for zooming moves increases and the overall length of the optical system increases, which hinders attempts to reduce the size of the optical system.

SUMMARY OF THE INVENTION

It is an object of the present invention to at least solve the above problems in the conventional technologies.

A zoom lens according to one aspect of the present invention includes sequentially from an object side a first lens group having a positive refractive power; a second lens group having a negative refractive power; a third lens group having a positive refractive power; a fourth lens group; and at least one lens group subsequent to the fourth lens group toward an image plane. The zoom lens zooms between a wide angle edge and a telephoto edge by varying intervals between the lens groups, along a direction of an optical axis; and corrects hand-shake that occurs with optical system vibration, by shifting any one among the entire second lens group and a portion of lenses forming the second lens group, in a direction that is substantially orthogonal to the optical axis. The zoom lens satisfies conditional expression (1) 0.5≦D2W×(−F2)/(Ft×tan(ωw))≦2.0 and condition expression (2) 90≦(F1×Ft)/(−F2×F3)≦200, where D2W is an interval between the second lens group and the third lens group at the wide angle edge, F1 is the focal length of the first lens group, F2 is the focal length of the second lens group, F3 is the focal length of the third lens group, Ft is the focal length of the optical system overall at the telephoto edge, and cow is a half-angle at the wide angle edge.

The other objects, features, and advantages of the present invention are specifically set forth in or will become apparent from the following detailed description of the invention when read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view along an optical axis, depicting a configuration of a zoom lens according to a first embodiment;

FIG. 2 is a diagram of various types of aberration in the zoom lens according to the first embodiment;

FIG. 3 is a cross sectional view along the optical axis, depicting a configuration of the zoom lens according to a second embodiment;

FIG. 4 is a diagram of various types of aberration in the zoom lens according to the second embodiment;

FIG. 5 is a cross sectional view along the optical axis, depicting a configuration of the zoom lens according to a third embodiment;

FIG. 6 is a diagram of various types of aberration in the zoom lens according to the third embodiment;

FIG. 7 is a cross sectional view along the optical axis, depicting a configuration of the zoom lens according to a fourth embodiment;

FIG. 8 is a diagram of various types of aberration in the zoom lens according to the fourth embodiment;

FIG. 9 is a cross sectional view along the optical axis, depicting a configuration of the zoom lens according to a fifth embodiment; and

FIG. 10 is a diagram of various types of aberration in the zoom lens according to the fifth embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of a zoom lens according to the present invention will be described in detail with reference to the accompanying drawings.

A zoom lens according to the present invention includes sequentially from an object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group, and 1 or more lens groups subsequent to the fourth lens group, toward an image plane. Zooming from a wide angle edge to a telephoto edge is performed by changing intervals between the lens groups, along a direction of the optical axis. Image blur that occurs with optical system vibration consequent to hand-shake is corrected by shifting (moving) the entire second lens group or a portion of the lenses forming the second lens group, in a direction that is substantially orthogonal to the optical axis. The fourth lens group may have a negative refractive power.

One object of the present invention is to provide a compact zoom lens having a high zoom ratio and a favorable anti-shake correction function. To achieve such an object, the following conditions are set.

In the zoom lens according to the present invention, the following conditional expressions are preferably satisfied, where D2W is the interval between the second lens group and the third lens group at the wide angle edge; F1 is the focal length of the first lens group; F2 is the focal length of the second lens group; F3 is the focal length of the third lens group; Ft is the focal length of the optical system overall at the telephoto edge; and ωw is the half-angle at the wide angle edge.

0.5≦D2W×(−F2)/(Ft×tan(ωw))≦2.0  (1)

90≦(F1×Ft)/(−F2×F3)≦200  (2)

Conditional expression (1) prescribes a condition to improve imaging performance, facilitated by reductions in the diameter and overall length of the optical system.

Below the lower limit of conditional expression (1), the interval between the second lens group and the third lens group at the wide angle edge becomes too narrow, or the power (inverse of the focal length) of the second lens group becomes too strong. In some cases, both may occur. Therefore, although reducing the overall length of the optical system is advantageous, chromatic difference of magnification and coma occurring at the wide angle edge become difficult to correct. Meanwhile, above the upper limit of conditional expression (1), although the correction of various types of aberration becomes favorable, the diameter of the second lens group increases, making the second lens group heaving. In the zoom lens according to the present invention, the entire second lens group or a portion of the lenses forming the second lens group has a function as an anti-shake group, and corrects image blur that occurs with optical system vibrations. Consequently, if the weight of the anti-shake group increases, the power consumption of the driving mechanism that drives the anti-shake group also increases, and therefore, is not desirable.

By satisfying conditional expression (1) within the following range, even more favorable effects can be expected.

0.8≦D2W×(−F2)/(Ft×tan(ωw))≦1.8  (1a)

By satisfying the range prescribed by conditional expression (1a), a smaller diameter and shorter overall length of the optical system can be facilitated while enabling improved imaging performance.

By satisfying conditional expression (1a) within the following range, yet even more favorable effects can be expected.

1.0≦D2W×(−F2)/(Ft×tan(ωw))≦1.75  (1b)

By satisfying the range prescribed by conditional expression (1b), a smaller diameter and a shorter overall length of the optical system can be facilitated while enabling even further improvements in imaging performance.

Conditional expression (2) prescribes a condition for achieving both a high zoom ratio and compact size of the zoom lens while improving imaging performance.

Below the lower limit of conditional expression (2), the power of the second lens group and of the third lens group becomes too weak, making both a high zoom ratio and compact size (particularly the second lens group) difficult to achieve. Meanwhile, above the upper limit of conditional expression (2), although both a zoom ratio and a compact size of the zoom lens can be easily achieved, spherical aberration, coma, and chromatic difference of magnification become difficult to correct.

By satisfying conditional expression (2) within the following range, even more favorable effects can be expected.

95≦(F1×Ft)/(−F2×F3)≦170  (2a)

By satisfying the ranges prescribed by conditional expression (2a), both a high zoom ratio and a compact size of the zoom lens can be achieved while enabling imaging performance to be improved further.

By satisfying conditional expression (2a) within the following range, yet even more favorable effects can be expected.

102≦(F1×Ft)/(−F2×F3)≦150  (2b)

By satisfying the range prescribed by conditional expression (2b), both a high zoom ratio and a compact size of the zoom lens can be achieved while enabling even further improvements in imaging performance.

In the zoom lens, the following conditional expression is preferably satisfied, where BXt2 is the anti-shake coefficient (amount of image point shift/amount that anti-shake group is shifted) for the entire second lens group or a portion of the lenses forming the second lens group, at the telephoto edge; and ωw is the half-angle at the wide angle edge.

3.1≦BXt2×tan(ωw)≦10  (3)

Conditional expression (3) prescribes a condition for implementing a zoom lens that maintains a small optical system diameter while having favorable imaging performance at wide angles, by controlling the shift amount that the entire second lens group or a portion of the lenses forming the second lens group is shifted when image blur at the telephoto edge is corrected.

Below the lower limit of conditional expression (3), the anti-shake coefficient for the entire second lens group or a portion of the lenses forming the second lens group, which has a function as the anti-shake group, becomes too small. In particular, the distance that the anti-shake group is shifted when image blur at the telephoto edge is corrected becomes great. Consequently, the optical system diameter increases and as a result, the driving mechanism that drives the anti-shake group also has to be larger, which invites increases in the size of the lens barrel that supports the zoom lens and therefore, is not desirable. On the other hand, above the upper limit of conditional expression (3), the anti-shake coefficient of the anti-shake group becomes large, which enables the distance that the anti-shake group is shifted to correct image blur at the telephoto edge to be suppressed and is advantageous in increasing the wide angle views of the optical system. Nonetheless, since the power of the second lens group becomes too strong, various types of aberration occurring at the wide angle edge become difficult to correct and is therefore, undesirable.

By satisfying conditional expression (3) within the following range, even more favorable effects can be expected.

3.2≦BXt2×tan(ωw)≦8.0  (3a)

By satisfying the range prescribed by conditional expression (3a), a compact zoom lens that has even more favorable imaging performance at wide angles can be implemented.

By satisfying conditional expression (3a) within the following range, yet even more favorable effects can be expected.

3.3≦BXt2×tan(ωw)≦6.0  (3b)

By satisfying the range prescribed by conditional expression (3b), a compact zoom lens having yet even more favorable imaging performance can be implemented.

In the zoom lens, the following conditional expression is preferably satisfied, where Z is the zoom ratio; Ymax is the maximum paraxial image height at the wide angle edge; and F2 is the focal length of the second lens group.

17≦(Z×Ymax)/(−F2)≦35  (4)

Conditional expression (4) prescribes a condition for achieving a wide angle zoom lens with a high zoom ratio while improving imaging performance.

Below the lower limit of conditional expression (4), the power of the second lens group becomes too weak, making both a high zoom ratio and wide angle views difficult to achieve on the zoom lens. Meanwhile, above the upper limit of conditional expression (4), although both a high zoom ratio and wide angles can be achieved for the zoom lens, various types of aberration such as chromatic difference of magnification, spherical aberration, etc. become difficult to correct and is therefore, not desirable.

By satisfying conditional expression (4) within the following range, even more favorable effects can be expected.

18≦(Z×Ymax)/(−F2)≦30  (4a)

By satisfying the range prescribed by conditional expression (4a), wide angles and a high zoom ratio of the zoom lens can be achieved while enabling imaging performance to be improved further.

By satisfying conditional expression (4a) within the following range, yet even more favorable effects can be expected.

19≦(Z×Ymax)/(−F2)≦25  (4b)

By satisfying the range prescribed by conditional expression (4b), wide angles and a high zoom ratio of the zoom lens can be achieved while enabling even further improvements in imaging performance.

Further, in the zoom lens, the following conditional expression is preferably satisfied, where F2 is the focal length of the second lens group; F4 is the focal length of the fourth lens group; D1T is the distance between the first lens group and the second lens group at the telephoto edge; and D3T is the distance between the third lens group and the fourth lens group at the telephoto edge.

0.5≦D3T/−F4≦3.0  (5)

3.5≦(D3T×D1T)/(F2×F4)≦15  (6)

Conditional expression (5) prescribes a condition for reducing the diameter and the overall length of the optical system without hindering the achievement of a high zoom ratio.

Below the lower limit of conditional expression (5), the interval between the third lens group and the fourth lens group at the telephoto edge becomes too wide and the overall length of the optical system increases. Further, the diameter of lens groups subsequent to the fourth lens group toward the image plane increases. Meanwhile, above the upper limit of conditional expression (5), the interval between third lens group and the fourth lens group at the telephoto edge becomes too narrow, hindering the achievement of a high zoom ratio. Further, the power of the fourth lens group becomes too weak and the overall length of the optical system at the telephoto edge increases. In either case, implementation of a compact zoom lens having a high zoom ratio becomes difficult.

By satisfying conditional expression (5) within the following range, even more favorable effects can be expected.

0.65≦D3T/−F4≦2.0  (5a)

By satisfying the range prescribed by conditional expression (5a), reductions in the diameter and overall length of the optical system are facilitated, enabling an even more compact optical system.

By satisfying conditional expression (5a) within the following range, yet even more favorable effects can be expected.

0.80≦D3T/−F4≦1.5  (5b)

By satisfying the range prescribed by conditional expression (5b), further reductions in the diameter and the overall length of the optical system are facilitated, enabling an even more compact optical system to be achieved.

Conditional expression (6) prescribes a condition for achieving a zoom lens that has a high zoom ratio and that is compact. Typically, when a high zoom ratio is attempted for a zoom lens, the distance that the lens group controlling zooming is moved increases and consequently, the overall length of the optical system increases, making a compact size of the optical system difficult. However, by satisfying conditional expression (6), the distance that the lens group controlling zooming is moved can be suppressed while enabling a reduction of the overall length of the optical system and a high zoom ratio.

Below the lower limit of conditional expression (6), the power of the second lens group and of the fourth lens group becomes too weak, and if a high zoom ratio is attempted to be achieved, the second lens group and the fourth lens group have to be moved a large distance when zooming is performed. Consequently, a high zoom ratio and a compact size for the zoom lens become difficult to achieve. Meanwhile, above the upper limit of conditional expression (6), the interval between the first lens group and the second lens group, and the interval between the third lens group and the fourth lens group become too large at the telephoto edge, causing the overall length of the optical system to increase, hindering achievement of a compact size for the optical system.

By satisfying conditional expression (6) within the following range, even more favorable effects can be expected.

4.5≦(D3T×D1T)/(F2×F4)≦12  (6a)

By satisfying the range prescribed by conditional expression (6a), the overall length of the optical system can be reduced further while enabling a high zoom ratio.

By satisfying conditional expression (6a) within the following range, yet even more favorable effects can be expected.

5.5≦(D3T×D1T)/(F2×F4)≦10  (6b)

By satisfying the range prescribed by conditional expression (6b), the overall length of the optical system can be reduced even further while enabling a high zoom ratio to be achieved.

As described, the zoom lens according to the present invention has the configuration described above, enabling a compact zoom lens that achieves wide angles and has a high zoom ratio to be implemented while further having a favorable anti-shake correction function. In particular, by satisfying the conditions described above, a compact size, wide angles, and a high zoom ratio are achieved while enabling imaging performance to be improved. Further, the distance that the anti-shake group is shifted at the time of image blur correction is suppressed and imaging performance is maintained during image blur correction.

With reference to the accompanying drawings embodiments of the zoom lens according to the present invention will be described in detail.

FIG. 1 is a cross sectional view along the optical axis, depicting a configuration of the zoom lens according to a first embodiment. The zoom lens includes sequentially from an object side that is nearest an object (not depicted), a first lens group G₁₁ having a positive refractive power, a second lens group G₁₂ having a negative refractive power, a third lens group G₁₃ having a positive refractive power, a fourth lens group G₁₄ having a negative refractive power, a fifth lens group G₁₅ having a positive refractive power, a sixth lens group G₁₆ having a negative refractive power. Further, between the second lens group G₁₂ and the third lens group G₁₃, an aperture stop S that prescribes a given diameter is disposed.

The first lens group G₁₁ includes sequentially from the object side, a negative lens L₁₁₁, a positive lens L₁₁₂, and a positive lens L₁₁₃. The negative lens L₁₁₁ and the positive lens L₁₁₂ are cemented.

The second lens group G₁₂ includes sequentially from the object side, a negative lens L₁₂₁, a negative lens L₁₂₂, a positive lens L₁₂₃, and a negative lens L₁₂₄. The negative lens L₁₂₂ and the positive lens L₁₂₃ are cemented. Further, both surfaces of the negative lens L₁₂₄ are aspheric.

The third lens group G₁₃ includes sequentially from the object side, a positive lens L₁₃₁, a negative lens L₁₃₂, and a positive lens L₁₃₃. The positive lens L₁₃₁ and the negative lens L₁₃₂ are cemented. Further, both surfaces of the positive lens L₁₃₃ are aspheric.

The fourth lens group G₁₄ includes sequentially from the object side, a negative lens L₁₄₁ and a positive lens L₁₄₂. The negative lens L₁₄₁ and positive lens L₁₄₂ are cemented.

The fifth lens group G₁₅ includes sequentially from the object side, a positive lens L₁₅₁ and a negative lens L₁₅₂. On the positive lens L₁₅₁, the surface facing toward the object is aspheric. The positive lens L₁₅₁ and the negative lens L₁₅₂ are cemented.

The sixth lens group G₁₆ is formed by a negative lens L₁₆₁.

The zoom lens moves the first lens group G₁₁ along the optical axis, from the image plane side to the object side; moves the second lens group G₁₂ along the optical axis, from the object side to the image plane side; moves the third lens group G₁₃ along the optical axis, from the image plane side to the object side; moves the fourth lens group G₁₄ along the optical axis, from the object side to the image plane side; and moves the fifth lens group G₁₅ along the optical axis, from the object side and back, to zoom from the wide angle edge to the telephoto edge.

The zoom lens moves the fifth lens group G₁₅ along the optical axis to perform focusing from infinity to the minimum object distance. Further, the zoom lens shifts the second lens group G₁₂ in a direction substantially orthogonal to the optical axis to correct image blur that occurs with optical system vibration consequent to hand-shake.

Various values related to the zoom lens according to the first embodiment are indicated below.

Focal length of entire zoom lens = 4.7885 (wide angle edge) to 43.0115 (intermediate position) to 186.8884 (Ft: telephoto edge) F number (Fno.) = 2.9 (wide angle edge) to 4.9 (intermediate position) to 6.4 (telephoto edge) Half-angle (ω) = 41.39 (ωw: wide angle edge) to 5.09 (intermediate position) to 1.17 (telephoto edge) Paraxial image height (Y) = 4.22 (Ymax: wide angle edge) to 3.83 (intermediate position) to 3.83 (telephoto edge) Focal length (F1) of first lens group G₁₁ = 76.1290 Focal length (F2) of second lens group G₁₂ = −8.0447 Focal length (F3) of third lens group G₁₃ = 16.9296 Focal length (F4) of fourth lens group G₁₄ = −26.5386 Focal length of fifth lens group G₁₅ = 19.5036 Focal length of sixth lens group G₁₆ = −60.5779 Zoom ratio (Z) = 39.0244 (Lens Data) r₁ = 104.6796 d₁ = 0.9000 nd₁ = 1.80610 υd₁ = 33.27 r₂ = 48.4361 d₂ = 4.5000 nd₂ = 1.43700 υd₂ = 95.10 r₃ = −183.2004 d₃ = 0.2000 r₄ = 43.2099 d₄ = 3.0000 nd₃ = 1.61800 υd₃ = 63.39 r₅ = 166.2488 d₅ = D(5) (variable) r₆ = 125.5141 d₆ = 0.5000 nd₄ = 1.69680 υd₄ = 55.46 r₇ = 8.2265 d₇ = 3.9590 r₈ = −32.1614 d₈ = 0.5000 nd₅ = 1.91082 υd₅ = 35.25 r₉ = 23.1845 d₉ = 2.3344 nd₆ = 1.94595 υd₆ = 17.98 r₁₀ = −39.9024 d₁₀ = 1.3656 r₁₁ = −14.2642 d₁₁ = 0.5000 nd₇ = 1.83441 υd₇ = 37.28 (aspheric surface) r₁₂ = −28.6551 d₁₂ = D(12) (variable) (aspheric surface) r₁₃ = ∞ d₁₃ = 0.4000 (aperture stop) r₁₄ = 27.1942 d₁₄ = 2.5640 nd₈ = 1.61800 υd₈ = 63.39 r₁₅ = −9.3597 d₁₅ = 0.5000 nd₉ = 1.74950 υd₉ = 35.04 r₁₆ = −58.6359 d₁₆ = 2.3973 r₁₇ = 62.5307 d₁₇ = 2.4432 nd₁₀ = 1.49710 υd₁₀ = 81.56 (aspheric surface) r₁₈ = −14.1291 d₁₈ = D(18) (variable) (aspheric surface) r₁₉ = −36.2539 d₁₉ = 0.6000 nd₁₁ = 1.74400 υd₁₁ = 44.90 r₂₀ = 10.2432 d₂₀ = 1.7000 nd₁₂ = 1.84666 υd₁₂ = 23.78 r₂₁ = 31.5852 d₂₁ = D(21) (variable) r₂₂ = 22.3669 d₂₂ = 3.5000 nd₁₃ = 1.49710 υd₁₃ = 81.56 (aspheric surface) r₂₃ = −8.8079 d₂₃ = 0.7000 nd₁₄ = 1.84666 υd₁₄ = 23.78 r₂₄ = −12.1131 d₂₄ = D(24) (variable) r₂₅ = −15.0000 d₂₅ = 0.7000 nd₁₅ = 1.84666 υd₁₅ = 23.78 r₂₆ = −21.6538 d₂₆ = D(26) (variable) r₂₇ = ∞ (image plane) Constant of cone (k) and Aspheric coefficients (A, B, C, D, E, F) (eleventh plane) k = 1.0000, A = 0, B = 1.45339 × 10⁻⁴, C = −6.22182 × 10⁻⁶, D = 4.06493 × 10⁻⁸, E = 6.50599 × 10⁻¹⁰, F = −6.52539 × 10⁻¹² (twelfth plane) k = 1.0000, A = 0, B = 8.14642 × 10⁻⁵, C = −6.44794 × 10⁻⁶, D = 6.78926 × 10⁻⁸, E = 0, F = 0 (seventeenth plane) k = 1.0000, A = 0, B = −1.75747 × 10⁻⁴, C = 5.53527 × 10⁻⁶, D = −2.97994 × 10⁻⁷, E = 3.72276 × 10⁻⁹, F = 0 (eighteenth plane) k = 1.0000, A = 0, B = −7.65925 × 10⁻⁵, C = 4.63905 × 10⁻⁶, D = −2.43393 × 10⁻⁷, E = 2.79005 × 10⁻⁹, F = 0 (twenty-second plane) k = 1.0000, A = 0, B = −8.33779 × 10⁻⁵, C = 7.43779 × 10⁻⁷, D = −3.17595 × 10⁻⁸, E = 5.00716 × 10⁻¹⁰, F = 0 (Zoom Data) wide angle intermediate position telephoto D(5) 0.8000 40.5304 55.9335 D(12) 34.7488 8.3490 0.1000 D(18) 2.3744 21.7219 30.8851 D(21) 11.0458 8.8163 10.6225 D(24) 7.1741 4.5967 2.1000 D(26) 7.0917 7.1141 7.1503

Interval (D2W) between second lens group G ₁₂ and third lens group G ₁₃ at wide angle edge=35.1488 tan(ωw)=0.8819D2W×(−F2)/(Ft×tan(ωw))=1.7155  (Values Related to Conditional Expression (1))

(F1×Ft)/(−F2×F3)=104.4660  (Values Related to Conditional Expression (2))

Anti-shake coefficient (BXt2) for second lens group G ₁₂ overall at telephoto edge=4.8296BXt2×tan(ωw)=4.2594  (Values Related to Conditional Expression (3))

(Z×Ymax)/(−F2)=20.4885  (Values Related to Conditional Expression (4))

Distance (D3T) between third lens group G ₁₃ and fourth lens group G ₁₄ at telephoto edge=30.8851D3T/−F4=1.1638  (Values Related to Conditional Expression (5))

Distance (D1T) between first lens group G ₁₁ and second lens group G ₁₂ at telephoto edge=55.9335  (Values Related to Conditional Expression (6))

(D3T×D1T)/(F2×F4)=8.0916

FIG. 2 is a diagram of various types of aberration in the zoom lens according to the first embodiment. Wavelength aberration corresponding to g-line (λ=435.83 nm), d-line (λ=587.56 nm), and C-line (λ=656.28 nm) is depicted. ΔS and ΔM in a portion depicting astigmatism, indicate aberration with respect to a sagittal image plane and a meridional image plane, respectively.

FIG. 3 is a cross sectional view along the optical axis, depicting a configuration of the zoom lens according to a second embodiment. The zoom lens includes sequentially from the object side, a first lens group G₂₁ having a positive refractive power, a second lens group G₂₂ having a negative refractive power, a third lens group G₂₃ having a positive refractive power, a fourth lens group G₂₄ having a negative refractive power, and a fifth lens group G₂₅ having a positive refractive power. Further, between the second lens group G₂₂ and the third lens group G₂₃, the aperture stop S that prescribes a given diameter is disposed.

The first lens group G₂₁ includes sequentially from the object side, a negative lens L₂₁₁, a positive lens L₂₁₂, and a positive lens L₂₁₃. The negative lens L₂₁₁ and the positive lens L₂₁₂ are cemented.

The second lens group G₂₂ includes sequentially from the object side, a negative lens L₂₂₁, a negative lens L₂₂₂, a positive lens L₂₂₃, and a negative lens L₂₂₄. Both surfaces of the negative lens L₂₂₁ and the surface on the negative lens L₂₂₄, facing toward the image plane are aspheric. The negative lens L₂₂₂ and the positive lens L₂₂₃ are cemented.

The third lens group G₂₃ includes sequentially from the object side, a positive lens L₂₃₁, a negative lens L₂₃₂, and a positive lens L₂₃₃. On the positive lens L₂₃₁, the surface facing toward the object is aspheric. The negative lens L₂₃₂ and the positive lens L₂₃₃ are aspheric.

The fourth lens group G₂₄ includes sequentially from the object side, a negative lens L₂₄₁ and a positive lens L₂₄₂. Both surfaces of the positive lens L₂₄₂ are aspheric.

The fifth lens group G₂₅ includes sequentially from the object side, a positive lens L₂₅₁ and a negative lens L₂₅₂. On the positive lens L₂₅₁, the surface facing toward the object is aspheric. The positive lens L₂₅₁ and the negative lens L₂₅₂ are cemented.

The zoom lens moves the first lens group G₂₁ along the optical axis, from the image plane side to the object side; moves the second lens group G₂₂ along the optical axis, from the object side to the image plane side; moves the third lens group G₂₃ along the optical axis, from the image plane side to the object side; moves the fourth lens group G₂₄ along the optical axis, from the object side to the image plane side; and moves the fifth lens group G₂₅ along the optical axis, from the object side and back, to zoom from the wide angle edge to the telephoto edge.

The zoom lens moves the fifth lens group G₂₅ along the optical axis to perform focusing from infinity to the minimum object distance. Further, the zoom lens shifts the second lens group G₂₂ in a direction substantially orthogonal to the optical axis to correct image blur that occurs with optical system vibration consequent to hand-shake.

Various values related to the zoom lens according to the second embodiment are indicated below.

Focal length of entire zoom lens = 4.6042 (wide angle edge) to 29.0000 (intermediate position) to 183.6480 (Ft: telephoto edge) F number (F no.) = 2.9 (wide angle edge) to 4.1 (intermediate position) to 6.0 (telephoto edge) Half-angle (ω) = 42.83 (ωw: wide angle edge) to 3.92 (intermediate position) to 1.20 (telephoto edge) Paraxial image height (Y) = 4.27 (Ymax: wide angle edge) to 3.92 (intermediate position) to 3.85 (telephoto edge) Focal length (F1) of first lens group G₂₁ = 69.2539 Focal length (F2) of second lens group G₂₂ = −7.0524 Focal length (F3) of third lens group G₂₃ = 16.4363 Focal length (F4) of fourth lens group G₂₄ = −28.2916 Focal length of fifth lens group G₂₅ = 19.6612 Zoom ratio (Z) = 39.8870 (Lens Data) r₁ = 86.8572 d₁ = 0.7000 nd₁ = 1.80610 υd₁ = 33.27 r₂ = 43.6362 d₂ = 6.2000 nd₂ = 1.43700 υd₂ = 95.10 r₃ = −236.7447 d₃ = 0.1000 r₄ = 40.2773 d₄ = 4.6000 nd₃ = 1.59282 υd₃ = 68.62 r₅ = 195.8458 d₅ = D(5) (variable) r₆ = 800.0000 d₆ = 0.5000 nd₄ = 1.69350 υd₄ = 53.20 (aspheric surface) r₇ = 10.0625 d₇ = 3.7212 (aspheric surface) r₈ = −61.9805 d₈ = 0.5000 nd₅ = 1.88100 υd₅ = 40.14 r₉ = 11.7228 d₉ = 2.3603 nd₆ = 1.94595 υd₆ = 17.98 r₁₀ = 102.9725 d₁₀ = 0.6542 r₁₁ = −76.9383 d₁₁ = 0.5000 nd₇ = 1.88202 υd₇ = 37.22 r₁₂ = 37.8481 d₁₂ = D(12) (aspheric surface) (variable) r₁₃ = ∞ d₁₃ = 1.0000 (aperture stop) r₁₄ = 25.1003 d₁₄ = 2.1400 nd₈ = 1.61881 υd₈ = 63.85 (aspheric surface) r₁₅ = −11.2849 d₁₅ = 0.3776 r₁₆ = −9.0000 d₁₆ = 0.5000 nd₉ = 1.61293 υd₉ = 36.96 r₁₇ = −118.8368 d₁₇ = 2.3053 nd₁₀ = 1.49700 υd₁₀ = 81.61 r₁₈ = −9.8194 d₁₈ = D(18) (variable) r₁₉ = −28.8403 d₁₉ = 0.5000 nd₁₁ = 1.80420 υd₁₁ = 46.50 r₂₀ = 38.6708 d₂₀ = 0.1000 r₂₁ = 12.1139 d₂₁ = 3.2122 nd₁₂ = 1.84681 υd₁₂ = 23.62 (aspheric surface) r₂₂ = 15.0000 d₂₂ = D(22) (aspheric surface) (variable) r₂₃ = 13.6781 d₂₃ = 5.0000 nd₁₃ = 1.49700 υd₁₃ = 81.61 (aspheric surface) r₂₄ = −9.6526 d₂₄ = 0.8000 nd₁₄ = 1.90366 υd₁₄ = 31.31 r₂₅ = −15.4094 d₂₅ = D(25) (variable) r₂₆ = ∞ (image plane) Constant of cone (k) and Aspheric coefficients (A, B, C, D, E, F) (sixth plane) k = 1.0000, A = 0, B = 2.85233 × 10⁻⁴, C = −3.72392 × 10⁻⁶, D = 3.26691 × 10⁻⁸, E = −3.17300 × 10⁻¹⁰, F = 1.46784 × 10⁻¹² (seventh plane) k = 1.0000, A = 0, B = 4.54486 × 10⁻⁴, C = 7.51122 × 10⁻⁷, D = 1.74448 × 10⁻⁷, E = −3.32774 × 10⁻¹⁰, F = 0 (twelfth plane) k = 1.0000, A = 0, B = −1.26158 × 10⁻⁴, C = −1.22232 × 10⁻⁶, D = −1.48733 × 10⁻¹⁰, E = −8.83503 × 10⁻¹¹, F = 2.56374 × 10⁻¹¹ (fourteenth plane) k = 5.9757, A = 0, B = −1.40409 × 10⁻⁴, C = −3.45339 × 10⁻⁷, D = 2.12846 × 10⁻⁸, E = −5.77296 × 10⁻¹⁰, F = 0 (twenty-first plane) k = 1.0000, A = 0, B = 1.42918 × 10⁻⁴, C = 8.28678 × 10⁻⁷, D = 6.90896 × 10⁻⁸, E = −8.64331 × 10⁻¹⁰, F = 0 (twenty-second plane) k = 1.0000, A = 0, B = 2.28550 × 10⁻⁴, C = 2.57220 × 10⁻⁶, D = 1.07616 × 10⁻⁷, E = −3.43355 × 10⁻¹¹, F = 0 (twenty-third plane) k = 1.0000, A = 0, B = −6.57548 × 10⁻⁵, C = 5.46170 × 10⁻⁸, D = 1.30576 × 10⁻⁸, E = −1.49895 × 10⁻¹⁰, F = 0 (Zoom Data) wide angle intermediate position telephoto D(5) 0.8000 33.0675 49.9719 D(12) 31.4258 10.7806 2.1556 D(18) 1.9471 17.5531 31.4720 D(22) 13.3575 9.6265 11.2984 D(25) 7.8285 11.5424 11.5424

Interval (D2W) between second lens group G ₂₂ and third lens group G ₂₃ at wide angle edge=32.4258 tan(ωw)=0.9270D2W×(−F2)/(Ft×tan(ωw))=1.3432  (Values Related to Conditional Expression (1))

(F1×Ft)/(−F2×F3)=109.7209  (Values Related to Conditional Expression (2))

Anti-shake coefficient (BXt2) for second lens group G ₂₂ overall at telephoto edge=4.8670BXt2×tan(ωw)=4.5119  (Values Related to Conditional Expression (3))

(Z×Ymax)/(−F2)=24.1402  (Values Related to Conditional Expression (4))

Distance (D3T) between third lens group G ₂₃ and fourth lens group G ₂₄ at telephoto edge=31.4720D3T/−F4=1.1124  (Values Related to Conditional Expression (5))

Distance (D1T) between first lens group G ₂₁ and second lens group G ₂₂ at telephoto edge=49.9719  (Values Related to Conditional Expression (6))

(D3T×D1T)/(F2×F4)=7.8824

FIG. 4 is a diagram of various types of aberration in the zoom lens according to the second embodiment. Wavelength aberration corresponding to g-line (λ=435.83 nm), d-line (λ=587.56 nm), and C-line (λ=656.28 nm) is depicted. ΔS and ΔM in a portion depicting astigmatism, indicate aberration with respect to a sagittal image plane and a meridional image plane, respectively.

FIG. 5 is a cross sectional view along the optical axis, depicting a configuration of the zoom lens according to a third embodiment. The zoom lens includes sequentially from the object side, a first lens group G₃₁ having a positive refractive power, a second lens group G₃₂ having a negative refractive power, a third lens group G₃₃ having a positive refractive power, a fourth lens group G₃₄ having a negative refractive power, a fifth lens group G₃₅ having a positive refractive power, and a sixth lens group G₃₆ having a negative refractive power. Further, between the second lens group G₃₂ and the third lens group G₃₃, the aperture stop S that prescribes a given diameter is disposed.

The first lens group G₃₁ includes sequentially from the object side, a negative lens L₃₁₁, a positive lens L₃₁₂, and a positive lens L₃₁₃. The negative lens L₃₁₁ and the positive lens L₃₁₂ are cemented.

The second lens group G₃₂ includes sequentially from the object side, a negative lens L₃₂₁, a negative lens L₃₂₂, a positive lens L₃₂₃, and a negative lens L₃₂₄. The negative lens L₃₂₂ and the positive lens L₃₂₃ are cemented.

The third lens group G₃₃ includes sequentially from the object side, a positive lens L₃₃₁, a negative lens L₃₃₂, and a positive lens L₃₃₃. The positive lens L₃₃₁ and the negative lens L₃₃₂ are cemented. Further, both surfaces of the positive lens L₃₃₃ are aspheric.

The fourth lens group G₃₄ includes sequentially from the object side, a negative lens L₃₄₁ and a positive lens L₃₄₂. The negative lens L₃₄₁ and the positive lens L₃₄₂ are cemented.

The fifth lens group G₃₅ includes sequentially from the object side, a positive lens L₃₅₁ and a negative lens L₃₅₂. On the positive lens L₃₅₁, the surface facing toward the object is aspheric. The positive lens L₃₅₁ and the negative lens L₃₅₂ are cemented.

The sixth lens group G₃₆ is formed by a negative lens L₃₆₁.

The zoom lens moves the first lens group G₃₁ along the optical axis, from the image plane side to the object side; moves the second lens group G₃₂ along the optical axis, from the object side to the image plane side; moves the third lens group G₃₃ along the optical axis, from the image plane side to the object side; moves the fourth lens group G₃₄ along the optical axis, from the object side to the image plane side; and moves the fifth lens group G₃₅ along the optical axis, from the object side and back, to zoom from the wide angle edge to the telephoto edge.

The zoom lens moves the fifth lens group G₃₅ along the optical axis to perform focusing from infinity to the minimum object distance. Further, the zoom lens shifts the second lens group G₃₂ in a direction substantially orthogonal to the optical axis to correct image blur that occurs with optical system vibration consequent to hand-shake.

Various values related to the zoom lens according to the third embodiment are indicated below.

Focal length of entire zoom lens = 4.7887 (wide angle edge) to 45.032 (intermediate position) to 204.6109 (Ft: telephoto edge) F number (F no.) = 2.9 (wide angle edge) to 5.2 (intermediate position) to 6.5 (telephoto edge) Half-angle (ω) = 41.70 (ωw: wide angle edge) to 4.81 (intermediate position) to 1.06 (telephoto edge) Paraxial image height (Y) = 4.27 (Ymax: wide angle edge) to 3.79 (intermediate position) to 3.79 (telephoto edge) Focal length (F1) of first lens group G₃₁ = 80.2143 Focal length (F2) of second lens group G₃₂ = −7.4858 Focal length (F3) of third lens group G₃₃ = 15.4591 Focal length (F4) of fourth lens group G₃₄ = −23.2278 Focal length of fifth lens group G₃₅ = 18.7207 Focal length of sixth lens group G₃₆ = −41.4617 Zoom ratio (Z) = 42.7252 (Lens Data) r₁ = 118.7286 d₁ = 1.0000 nd₁ = 1.80610 υd₁ = 33.27 r₂ = 52.6232 d₂ = 5.3000 nd₂ = 1.43700 υd₂ = 95.10 r₃ = −148.5460 d₃ = 0.2000 r₄ = 45.0241 d₄ = 3.6000 nd₃ = 1.61800 υd₃ = 63.39 r₅ = 150.3707 d₅ = D(5) (variable) r₆ = 40.5889 d₆ = 0.5000 nd₄ = 1.69680 υd₄ = 55.46 r₇ = 10.0218 d₇ = 4.4700 r₈ = −23.9466 d₈ = 0.5000 nd₅ = 1.91082 υd₅ = 35.25 r₉ = 11.0000 d₉ = 2.9736 nd₆ = 1.94595 υd₆ = 17.98 r₁₀ = −183.9563 d₁₀ = 1.5404 r₁₁ = −13.5647 d₁₁ = 0.5000 nd₇ = 1.90366 υd₇ = 31.31 r₁₂ = −25.5276 d₁₂ = D(12) (variable) r₁₃ = ∞ d₁₃ = 0.4000 (aperture stop) r₁₄ = 22.2366 d₁₄ = 2.6574 nd₈ = 1.61800 υd₈ = 63.39 r₁₅ = −9.1559 d₁₅ = 0.5000 nd₉ = 1.74950 υd₉ = 35.04 r₁₆ = −111.4891 d₁₆ = 2.8840 r₁₇ = 29.5535 d₁₇ = 2.0717 nd₁₀ = 1.49710 υd₁₀ = 81.56 (aspheric surface) r₁₈ = −14.3273 d₁₈ = D(18) (variable) (aspheric surface) r₁₉ = −44.1928 d₁₉ = 0.6000 nd₁₁ = 1.74400 υd₁₁ = 44.90 r₂₀ = 8.2752 d₂₀ = 1.7000 nd₁₂ = 1.84666 υd₁₂ = 23.78 r₂₁ = 22.0953 d₂₁ = D(21) (variable) r₂₂ = 18.4314 d₂₂ = 3.5000 nd₁₃ = 1.49710 υd₁₃ = 81.56 (aspheric surface) r₂₃ = −8.8357 d₂₃ = 0.7000 nd₁₄ = 1.84666 υd₁₄ = 23.78 r₂₄ = −12.5408 d₂₄ = D(24) (variable) r₂₅ = −15.0000 d₂₅ = 0.7000 nd₁₅ = 1.84666 υd₁₅ = 23.78 r₂₆ = −26.7521 d₂₆ = D(26) (variable) r₂₇ = ∞ (image plane) Constant of cone (k) and Aspheric coefficients (A, B, C, D, E, F) (seventeenth plane) k = 1.0000, A = 0, B = −1.01511 × 10⁻⁴, C = 3.78727 × 10⁻⁶, D = −1.96610 × 10⁻⁷, E = 4.41959 × 10⁻⁹, F = 0 (eighteenth plane) k = 1.0000, A = 0, B = 2.11066 × 10⁻⁵, C = 2.99520 × 10⁻⁶, D = −1.57582 × 10⁻⁷, E = 3.61863 × 10⁻⁹, F = 0 (twenty-second plane) k = 1.0000, A = 0, B = −8.11343 × 10⁻⁵, C = 4.92638 × 10⁻⁷, D = −1.99687 × 10⁻⁸, E = 3.40661 × 10⁻¹⁰, F = 0 (Zoom Data) wide angle intermediate position telephoto D(5) 0.8000 42.9524 59.3239 D(12) 33.0122 7.7431 0.1000 D(18) 2.4917 19.5447 25.5895 D(21) 11.0485 9.4848 11.5894 D(24) 7.1712 4.1811 2.1000 D(26) 5.0039 5.0246 5.0366

Interval (D2W) between second lens group G ₃₂ and third lens group G ₃₃ at wide angle edge=33.4122 tan(ωw)=0.8909D2W×(−F2)/(Ft×tan(ωw))=1.3722  (Values Related to Conditional Expression (1))

(F1×Ft)/(−F2×F3)=141.8268  (Values Related to Conditional Expression (2))

Anti-shake coefficient (BXt2) for second lens group G ₃₂ overall at telephoto edge=4.9762BXt2×tan(ωw)=4.4331  (Values Related to Conditional Expression (3))

(Z×Ymax)/(−F2)=24.3503  (Values Related to Conditional Expression (4))

Distance (D3T) between third lens group G ₃₃ and fourth lens group G ₃₄ at telephoto edge=25.5895D3T/−F4=1.1017  (Values Related to Conditional Expression (5))

Distance (D1T) between first lens group G ₃₁ and second lens group G ₃₂ at telephoto edge=59.3239  (Values Related to Conditional Expression (6))

(D3T×D1T)/(F2×F4)=8.7306

FIG. 6 is a diagram of various types of aberration in the zoom lens according to the third embodiment. Wavelength aberration corresponding to g-line (λ=435.83 nm), d-line (λ=587.56 nm), and C-line (λ=656.28 nm) is depicted. ΔS and ΔM in a portion depicting astigmatism, indicate aberration with respect to a sagittal image plane and a meridional image plane, respectively.

FIG. 7 is a cross sectional view along the optical axis, depicting a configuration of the zoom lens according to a fourth embodiment. The zoom lens includes sequentially from the object side, a first lens group G₄₁ having a positive refractive power, a second lens group G₄₂ having a negative refractive power, a third lens group G₄₃ having a positive refractive power, a fourth lens group G₄₄ having a negative refractive power, a fifth lens group G₄₅ having a positive refractive power, and a sixth lens group G₄₆ having a negative refractive power. Further, between the second lens group G₄₂ and the third lens group G₄₃, the aperture stop S that prescribes a given diameter is disposed.

The first lens group G₄₁ includes sequentially from the object side, a negative lens L₄₁₁, a positive lens L₄₁₂, and a positive lens L₄₁₃. The negative lens L₄₁₁ and the positive lens L₄₁₂ are cemented.

The second lens group G₄₂ includes sequentially from the object side, front group G_(42F) having positive refractive power and a rear group G_(42R) having negative refractive power. The front group G_(42F) includes sequentially from the object side, a negative lens L₄₂₁, a negative lens L₄₂₂, and a positive lens L₄₂₃. Both surfaces of the negative lens L₄₂₁ and the surface on the negative lens L₄₂₂, facing toward the object are aspheric. The negative lens L₄₂₂ and the positive lens L₄₂₃ are cemented. The rear group G_(42R) is formed by a negative lens L₄₂₄. Both surfaces of the negative lens L₄₂₄ are aspheric.

The third lens group G₄₃ includes sequentially from the object side, a positive lens L₄₃₁, a negative lens L₄₃₂, and a positive lens L₄₃₃. The positive lens L₄₃₁ and the negative lens L₄₃₂ are cemented. Further, both surfaces of the positive lens L₄₃₃ are aspheric.

The fourth lens group G₄₄ includes sequentially from the object side, a negative lens L₄₄₁ and a positive lens L₄₄₂. The negative lens L₄₄₁ and the positive lens L₄₄₂ are cemented.

The fifth lens group G₄₅ includes sequentially from the object side, a positive lens L₄₅₁ and a negative lens L₄₅₂. On the positive lens L₄₅₁, the surface facing toward the object is aspheric. The positive lens L₄₅₁ and the negative lens L₄₅₂ are cemented.

The sixth lens group G₄₆ is formed by a negative lens L₄₆₁.

The zoom lens moves the first lens group G₄₁ along the optical axis, from the image plane side to the object side; moves the second lens group G₄₂ along the optical axis, from the object side to the image plane side; moves the third lens group G₄₃ along the optical axis, from the image plane side to the object side; moves the fourth lens group G₄₄ along the optical axis, from the object side to the image plane side; and moves the fifth lens group G₄₅ along the optical axis, from the object side and back, to zoom from the wide angle edge to the telephoto edge.

The zoom lens moves the fifth lens group G₄₅ along the optical axis to perform focusing from infinity to the minimum object distance. Further, the zoom lens moves the front group G_(42F) of the second lens group G₄₂ in a direction substantially orthogonal to the optical axis to correct image blur that occurs with optical system vibration consequent to hand-shake.

Various values related to the zoom lens according to the fourth embodiment are indicated below.

Focal length of entire zoom lens = 4.7549 (wide angle edge) to 29.0164 (intermediate position) to 198.539 (Ft: telephoto edge) F number (F no.) = 2.9 (wide angle edge) to 4.5 (intermediate position) to 6.1 (telephoto edge) Half-angle (ω) = 41.91 (ωw: wide angle edge) to 7.51 (intermediate position) to 1.10 (telephoto edge) Paraxial image height (Y) = 4.268 (Ymax: wide angle edge) to 3.825 (intermediate position) to 3.802 (telephoto edge Focal length (F1) of first lens group G₄₁ = 80.8922 Focal length (F2) of second lens group G₄₂ = −8.1514 Focal length (F3) of third lens group G₄₃ = 15.9264 Focal length (F4) of fourth lens group G₄₄ = −22.5499 Focal length of fifth lens group G₄₅ = 18.8794 Focal length of sixth lens group G₄₆ = −47.9414 Zoom ratio (Z) = 41.7537 (Lens Data) r₁ = 99.5194 d₁ = 1.0000 nd₁ = 1.80610 υd₁ = 33.27 r₂ = 50.4174 d₂ = 5.6000 nd₂ = 1.43700 υd₂ = 95.10 r₃ = −283.2720 d₃ = 0.2000 r₄ = 46.0953 d₄ = 4.1000 nd₃ = 1.59282 υd₃ = 68.62 r₅ = 206.4139 d₅ = D(5) (variable) r₆ = 28.4100 d₆ = 0.5000 nd₄ = 1.80139 υd₄ = 45.45 (aspheric surface) r₇ = 9.4498 d₇ = 4.5520 (aspheric surface) r₈ = −17.2432 d₈ = 0.5000 nd₅ = 1.85135 υd₅ = 40.10 (aspheric surface) r₉ = 20.0002 d₉ = 2.2937 nd₆ = 1.94595 υd₆ = 17.98 r₁₀ = −74.9586 d₁₀ = 1.3235 r₁₁ = −32.1740 d₁₁ = 0.5000 nd₇ = 1.72903 υd₇ = 54.04 (aspheric surface) r₁₂ = −200.0000 d₁₂ = D(12) (variable) (aspheric surface) r₁₃ = ∞ d₁₃ = 0.4000 (aperture stop) r₁₄ = 26.7974 d₁₄ = 2.6066 nd₈ = 1.61800 υd₈ = 63.39 r₁₅ = −9.7147 d₁₅ = 0.5000 nd₉ = 1.74950 υd₉ = 35.04 r₁₆ = −47.5489 d₁₆ = 2.5000 r₁₇ = 36.1276 d₁₇ = 1.9301 nd₁₀ = 1.49710 υd₁₀ = 81.56 (aspheric surface) r₁₈ = −16.6859 d₁₈ = D(18) (variable) (aspheric surface) r₁₉ = −35.9822 d₁₉ = 0.5000 nd₁₁ = 1.74330 υd₁₁ = 49.22 r₂₀ = 8.1860 d₂₀ = 1.6953 nd₁₂ = 1.90366 υd₁₂ = 31.31 r₂₁ = 20.9654 d₂₁ = D(21) (variable) r₂₂ = 17.4717 d₂₂ = 4.3000 nd₁₃ = 1.49710 υd₁₃ = 81.56 (aspheric surface) r₂₃ = −8.3849 d₂₃ = 0.7000 nd₁₄ = 1.90366 υd₁₄ = 31.31 r₂₄ = −12.0966 d₂₄ = D(24) (variable) r₂₅ = −17.3657 d₂₅ = 0.7000 nd₁₅ = 1.84666 υd₁₅ = 23.78 r₂₆ = −30.9116 d₂₆ = D(26) (variable) r₂₇ = ∞ (image plane) Constant of cone (k) and Aspheric coefficients (A, B, C, D, E, F) (sixth plane) k = −72.6590, A = 0, B = 1.39938 × 10⁻⁴, C = −2.54371 × 10⁻⁶, D = 4.33966 × 10⁻⁸, E = −4.15406 × 10⁻¹⁰, F = 1.88610 × 10⁻¹² (seventh plane) k = −0.5118, A = 0, B = 3.06961 × 10⁻⁵, C = 1.41245 × 10⁻⁵, D = −4.25273 × 10⁻⁷, E = 1.05745 × 10⁻⁸, F = −7.85149 × 10⁻¹¹ (eighth plane) k = 1.0000, A = 0, B = 1.14758 × 10⁻⁴, C = −1.42956 × 10⁻⁶, D = 1.95709 × 10⁻⁷, E = −4.50142 × 10⁻⁹, F = 1.15154 × 10⁻¹¹ (eleventh plane) k = 1.0000, A = 0, B = 2.45048 × 10⁻⁴, C = −1.43869 × 10⁻⁵, D = 4.58757 × 10⁻⁸, E = 7.75921 × 10⁻⁹, F = −9.21631 × 10⁻¹¹ (twelfth plane) k = 1.0000, A = 0, B = 2.54443 × 10⁻⁴, C = −1.71144 × 10⁻⁵, D = 3.38852 × 10⁻⁷, E = −2.04437 × 10⁻⁹, F = 0 (seventeenth plane) k = 3.6599, A = 0, B = −1.42745 × 10⁻⁴, C = 8.50625 × 10⁻⁶, D = −4.56478 × 10⁻⁷, E = 8.64884 × 10⁻⁹, F = 0 (eighteenth plane) k = 1.0000, A = 0, B = −5.92382 × 10⁻⁵, C = 8.20070 × 10⁻⁶, D = −4.29042 × 10⁻⁷, E = 7.95619 × 10⁻⁹, F = 0 (twenty-second plane) k = 1.0000, A = 0, B = −7.99966 × 10⁻⁵, C = 9.05381 × 10⁻⁷, D = −3.22230 × 10⁻⁸, E = 5.49078 × 10⁻¹⁰, F = 0 (Zoom Data) wide angle intermediate position telephoto D(5) 0.8000 36.5962 58.6343 D(12) 37.8121 13.3712 0.1000 D(18) 2.2579 13.5450 25.9125 D(21) 11.0481 12.7909 11.3729 D(24) 7.0717 3.8218 2.0000 D(26) 5.5710 5.6120 5.5867

Interval (D2W) between second lens group G ₄₂ and third lens group G ₄₃ at wide angle edge=38.2121 tan(ωw)=0.8974D2W×(−F2)/(Ft×tan(ωw))=1.7483  (Values Related to Conditional Expression (1))

(F1×Ft)/(−F2×F3)=123.7094  (Values Related to Conditional Expression (2))

Anti-shake coefficient (BXt2) for front group G _(42F) of second lens group G ₄₂ at telephoto edge=3.8616BXt2×tan(ωw)=3.4652  (Values Related to Conditional Expression (3))

(Z×Ymax)/(−F2)=21.8563  (Values Related to Conditional Expression (4))

Distance (D3T) between third lens group G ₄₃ and fourth lens group G ₄₄ at telephoto edge=25.9125D3T/−F4=1.1491  (Values Related to Conditional Expression (5))

Distance (D1T) between first lens group G ₄₁ and second lens group G ₄₂ at telephoto edge=58.6343  (Values Related to Conditional Expression (6))

(D3T×D1T)/(F2×F4)=8.2658

FIG. 8 is a diagram of various types of aberration in the zoom lens according to the fourth embodiment. Wavelength aberration corresponding to g-line (λ=435.83 nm), d-line (λ=587.56 nm), and C-line (λ=656.28 nm) is depicted. ΔS and ΔM in a portion depicting astigmatism, indicate aberration with respect to a sagittal image plane and a meridional image plane, respectively.

FIG. 9 is a cross sectional view along the optical axis, depicting a configuration of the zoom lens according to a fifth embodiment. The zoom lens includes sequentially from the object side, a first lens group G₅₁ having a positive refractive power, a second lens group G₅₂ having a negative refractive power, a third lens group G₅₃ having a positive refractive power, a fourth lens group G₅₄ having a negative refractive power, a fifth lens group G₅₅ having a positive refractive power, and a sixth lens group G₅₆ having a negative refractive power. Further, between the second lens group G₅₂ and the third lens group G₅₃, the aperture stop S that prescribes a given diameter is disposed.

The first lens group G₅₁ includes sequentially from the object side, a negative lens L₅₁₁, a positive lens L₅₁₂, and a positive lens L₅₁₃. The negative lens L₅₁₁ and the positive lens L₅₁₂ are cemented.

The second lens group G₅₂ includes sequentially from the object side, a negative lens L₅₂₁, a negative lens L₅₂₂, a positive lens L₅₂₃, and a negative lens L₅₂₄. The negative lens L₅₂₂ and the positive lens L₅₂₃ are cemented. Furthermore, both sides of the negative lens L₅₂₄ are aspheric.

The third lens group G₅₃ includes sequentially from the object side, a positive lens L₅₃₁, a negative lens L₅₃₂, and a positive lens L₅₃₃. The positive lens L₅₃₁ and the negative lens L₅₃₂ are cemented. Furthermore, both surfaces of the positive lens L₅₃₃ are cemented.

The fourth lens group G₅₄ includes sequentially from the object side, a negative lens L₅₄₁ and a positive lens L₅₄₂. The negative lens L₅₄₁ and the positive lens L₅₄₂ are cemented.

The fifth lens group G₅₅ includes sequentially from the object side, a positive lens L₅₅₁ and a negative lens L₅₅₂. On the positive lens L₅₅₁, the surface facing toward the object is aspheric. The positive lens L₅₅₁ and the negative lens L₅₅₂ are cemented.

The sixth lens group G₅₆ is formed by a negative lens L₅₆₁.

The zoom lens moves the first lens group G₅₁ along the optical axis, from the image plane side to the object side; moves the second lens group G₅₂ along the optical axis, from the object side to the image plane side; moves the third lens group G₅₃ along the optical axis, from the image plane side to the object side; moves the fourth lens group G₅₄ along the optical axis, from the object side to the image plane side; and moves the fifth lens group G₅₅ along the optical axis, from the object side and back, to zoom from the wide angle edge to the telephoto edge.

The zoom lens moves the fifth lens group G₅₅ along the optical axis to perform focusing from infinity to the minimum object distance. Further, the zoom lens shifts the second lens group G₅₂ in a direction substantially orthogonal to the optical axis to correct image blur that occurs with optical system vibration consequent to hand-shake.

Various values related to the zoom lens according the fifth embodiment are indicated below.

Focal length of entire zoom lens = 4.7395 (wide angle edge) to 43.0117 (intermediate position) to 203.3847 (Ft: telephoto edge) F number (F no.) = 2.9 (wide angle edge) to 5.0 (intermediate position) to 6.5(telephoto edge) Half-angle (ω) = 41.99 (ωw: wide angle edge) to 4.93 (intermediate position) to 1.07 (telephoto edge) Paraxial image height(Y) = 4.27 (Ymax: wide angle edge) to 3.71 (intermediate position) to 3.80 (telephoto edge) Focal length (F1) of first lens group G₅₁ = 75.1144 Focal length (F2) of second lens group G₅₂ = −7.8437 Focal length (F3) of third lens group G₅₃ = 17.1792 Focal length (F4) of fourth lens group G₅₄ = −31.5511 Focal length of fifth lens group G₅₅ = 20.9376 Focal length of sixth lens group G₅₆ = −60.5410 Zoom ratio (Z) = 42.9173 (Lens Data) r₁ = 97.6858 d₁ = 1.0000 nd₁ = 1.80610 υd₁ = 33.27 r₂ = 46.5191 d₂ = 5.2000 nd₂ = 1.43700 υd₂ = 95.10 r₃ = −238.2465 d₃ = 0.2000 r₄ = 43.4953 d₄ = 3.7000 nd₃ = 1.61800 υd₃ = 63.39 r₅ = 198.1204 d₅ = D(5) (variable) r₆ = 72.3886 d₆ = 0.5000 nd₄ = 1.69680 υd₄ = 55.46 r₇ = 8.6209 d₇ = 4.3094 r₈ = −21.7879 d₈ = 0.5000 nd₅ = 1.91082 υd₅ = 35.25 r₉ = −21.7879 d₉ = 2.4000 nd₆ = 1.94595 υd₆ = 17.98 r₁₀ = −36.7935 d₁₀ = 1.4363 r₁₁ = −13.5739 d₁₁ = 0.5000 nd₇ = 1.83441 υd₇ = 37.28 (aspheric surface) r₁₂ = −24.5104 d₁₂ = D(12) (variable) (aspheric surface) r₁₃ = ∞ d₁₃ = 0.4000 (aperture stop) r₁₄ = 22.7781 d₁₄ = 2.5000 nd₈ = 1.59349 υd₈ = 67.00 r₁₅ = −10.8005 d₁₅ = 0.5000 nd₉ = 1.80610 υd₉ = 33.27 r₁₆ = −40.9889 d₁₆ = 2.7295 r₁₇ = 108.2255 d₁₇ = 2.3500 nd₁₀ = 1.49710 υd₁₀ = 81.56 (aspheric surface) r₁₈ = −14.8586 d₁₈ = D(18) (variable) (aspheric surface) r₁₉ = −40.8236 d₁₉ = 0.6000 nd₁₁ = 1.72342 υd₁₁ = 37.99 r₂₀ = 9.2151 d₂₀ = 2.0000 nd₁₂ = 1.84666 υd₁₂ = 23.78 r₂₁ = 31.1982 d₂₁ = D(21) (variable) r₂₂ = 19.8859 d₂₂ = 3.6000 nd₁₃ = 1.49710 υd₁₃ = 81.56 (aspheric surface) r₂₃ = −9.5445 d₂₃ = 0.7000 nd₁₄ = 1.84666 υd₁₄ = 23.78 r₂₄ = −13.9684 d₂₄ = D(24) (variable) r₂₅ = −15.0000 d₂₅ = 0.7000 nd₁₅ = 1.80518 υd₁₅ = 25.46 r₂₆ = −22.1184 d₂₆ = D(26) (variable) r₂₇ = ∞ (image plane) Constant of cone (k) and Aspheric coefficients (A, B, C, D, E, F) (eleventh plane) k = 1.0000, A = 0, B = 9.22813 × 10⁻⁵, C = −5.19243 × 10⁻⁶, D = 1.61167 × 10⁻⁸, E = 1.38709 × 10⁻⁹, F = −1.11770 × 10⁻¹¹ (twelfth plane) k = 1.0000, A = 0, B = 5.80683 × 10⁻⁵, C = −5.76820 × 10⁻⁶, D = 7.48974 × 10⁻⁸, E = 0, F = 0 (seventeenth plane) k = 1.0000, A = 0, B = −8.93615 × 10⁻⁵, C = 2.81304 × 10⁻⁶, D = −1.77829 × 10⁻⁷, E = 3.99999 × 10⁻⁹, F = 0 (eighteenth plane) k = 1.0000, A = 0, B = 2.29650 × 10⁻⁶, C = 2.11271 × 10⁻⁶, D = −1.30186 × 10⁻⁷, E = 2.86026 × 10⁻⁹, F = 0 (twenty-second plane) k = 1.0000, A = 0, B = −7.25054 × 10⁻⁵, C = 1.47968 × 10⁻⁶, D = −6.55813 × 10⁻⁸, E = 1.06529 × 10⁻⁹, F = 0 (Zoom Data) wide angle intermediate position telephoto D(5) 0.9000 40.5237 55.5639 D(12) 35.1240 9.4972 0.1000 D(18) 2.3271 20.9398 28.5219 D(21) 11.0524 10.3393 12.7390 D(24) 7.1674 4.0999 2.1000 D(26) 4.9956 5.0139 5.0476

Interval (D2W) between second lens group G ₅₂ and third lens group G ₅₃ at wide angle edge=35.5240 tan(ωw)=0.9000D2W×(−F2)/(Ft×tan(ωw))=1.5223  (Values Related to Conditional Expression (1))

(F1×Ft)/(−F2×F3)=113.3752  (Values Related to Conditional Expression (2))

Anti-shake coefficient (BXt2) for second lens group G ₅₂ overall at telephoto edge=4.9546BXt2×tan(ωw)=4.4589  (Values Related to Conditional Expression (3))

(Z×Ymax)/(−F2)=23.3356  (Values Related to Conditional Expression (4))

Distance (D3T) between third lens group G ₅₃ and fourth lens group G ₅₄ at telephoto edge=28.5219D3T/−F4=0.9040  (Values Related to Conditional Expression (5))

Distance (D1T) between first lens group G ₅₁ and second lens group G ₅₂ at telephoto edge=55.5639  (Values Related to Conditional Expression (6))

(D3T×D1T)/(F2×F4)=6.4038

FIG. 10 is a diagram of various types of aberration in the zoom lens according to the fifth embodiment. Wavelength aberration corresponding to g-line (λ=435.83 nm), d-line (λ=587.56 nm), and C-line (λ=656.28 nm) is depicted. ΔS and ΔM in a portion depicting astigmatism, indicate aberration with respect to a sagittal image plane and a meridional image plane, respectively.

Among the values for each of the examples above, r₁, r₂, . . . indicate radii of curvature for each lens, diaphragm surface, etc.; d₁, d₂, . . . indicate the thickness of the lenses, diaphragm, etc. or the distance between surfaces thereof; nd₁, nd₂, . . . indicate the refraction index of each lens with respect to the d-line (λ=587.56 nm), and υd₁, υd₂, . . . indicate the Abbe number with respect to the d-line (λ=587.56 nm). Lengths are indicated in units of [mm] and angles are indicated in [degrees].

Each of the aspheric surfaces described above is expressed by equation [1], where X represents a direction of the optical axis; h represents a height from the optical axis; k is the constant of the cone, and A, B, C, D, E, and F are second, fourth, sixth, eighth, tenth, and twelfth order aspheric coefficients. The direction of light is assumed to be positive.

$\begin{matrix} {X = {\frac{h^{2}/R}{1 + \sqrt{1 - {\left( {1 + k} \right)\left( {h/R} \right)^{2}}}} + {Ah}^{2} + {Bh}^{4} + {Ch}^{6} + {Dh}^{8} + {Eh}^{10} + {Fh}^{12}}} & \lbrack 1\rbrack \end{matrix}$

As described, by satisfying each of the conditional expression above, the zoom lens according to each of the embodiments achieves a compact size, wide angle views (in particular, the angle of view at the wide angle edge is 75 degrees or more), and a high zoom ratio (on the order of 40 times) while enabling imaging performance to be improved. Further, with the zoom lens, the amount that the anti-shake group is shifted when image blur is corrected can be suppressed and the imaging performance when image blur is corrected can be maintained. Moreover, in the zoom lens, aspheric lenses and cemented lenses are disposed as necessary, enabling imaging performance to be further improved.

As described, the zoom lens according to the present invention is useful in digital imaging apparatuses such as digital still cameras and digital video cameras; and is particularly suitable for digital imaging apparatuses of which a compact size and high zoom ratio are demanded.

Although the invention has been described with respect to a specific embodiment for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art which fairly fall within the basic teaching herein set forth.

The present document incorporates by reference the entire contents of Japanese priority document, 2013-020888 filed in Japan on Feb. 5, 2013. 

What is claimed is:
 1. A zoom lens comprising sequentially from an object side: a first lens group having a positive refractive power; a second lens group having a negative refractive power; a third lens group having a positive refractive power; a fourth lens group; and at least one lens group subsequent to the fourth lens group toward an image plane, wherein zooming between a wide angle edge and a telephoto edge is performed by varying intervals between the lens groups, along a direction of an optical axis, correction of hand-shake occurring with optical system vibration is performed by shifting any one among the entire second lens group and a portion of lenses forming the second lens group, in a direction that is substantially orthogonal to the optical axis, and conditional expression (1) 0.5≦D2W×(−F2)/(Ft×tan(ωw))≦2.0 and condition expression (2) 90≦(F1×Ft)/(−F2×F3)≦200 are satisfied, where D2W is an interval between the second lens group and the third lens group at the wide angle edge, F1 is the focal length of the first lens group, F2 is the focal length of the second lens group, F3 is the focal length of the third lens group, Ft is the focal length of the optical system overall at the telephoto edge, and ωw is a half-angle at the wide angle edge.
 2. The zoom lens according to claim 1, wherein the fourth lens group has a negative refractive power.
 3. The zoom lens according to claim 1, wherein conditional expression (3) 3.1≦BXt2×tan(ωw)≦10 is satisfied, where BXt2 is an anti-shake coefficient (amount of image point shift/amount that an anti-shake group is shifted) for any one among the entire second lens group and a portion of the lenses forming the second lens group, at the telephoto edge.
 4. The zoom lens according to claim 1, wherein conditional expression (4) 17≦(Z×Ymax)/(−F2)≦35 is satisfied, where Z is a zoom ratio and Ymax is a maximum paraxial image height at the wide angle edge.
 5. The zoom lens according to claim 1, wherein conditional expression (5) 0.5≦D3T/−F4≦3.0 and conditional expression (6) 3.5≦(D3T×D1T)/(F2×F4)≦15 are satisfied, where F4 is the focal length of the fourth lens group; D1T is a distance between the first lens group and the second lens group, at the telephoto edge; and D3T is a distance between the third lens group and the fourth lens group. 